Using nitrate isotope to trace the nitrogen pollution in Chanhe and Laohe river

Nitrogen isotope tracing method was used to identify the dominate contamination source of Chanhe River and Laohe River.The results showed that the δ15 N-NO 3-values of Chanhe and Laohe River from upper to lower stream were 1.3‰ to 9.0‰ and 3.3‰ to 7.4‰,respectively.And the δ15 N values of the sewage samples were 11.5‰ and 11.1‰.Through comparing the upper and lower stream δ15 N value with the sewage sample,this research found that nitrate isotope indicated the contamination sources,and the nitrate isotope value could provide more valuable messages relative to the nitrate concentration.Meanwhile,this research approximately divided the main nitrogen source in different river drainage areas.These results can offer important information for investigating the nitrate pollution and nutrient runoff in this area.